Background: School bullying has a national prevalence of 9 to 54 percent and is thought to be one of the precursors of youth violence. Bullying is characterized by aggressive or intent-to-harm behaviors performed repeatedly over time. It occurs in interpersonal relationships where a power imbalance is present. School bullying is thought to have potential psychopathologic outcomes in the bully and the victim, and it can lead to more serious violent behaviors. Previous studies have failed to demonstrate cause and effect between adverse outcomes and bullying. Kim and associates assessed the causal relationship between school bullying and subsequent psychopathologic behaviors.

The Study: Participants in the study were seventh and eighth grade students in two large Korean public school systems. Most of the 1,655 students who completed the study came from intact families of middle socioeconomic status. All students were asked to complete surveys at the start of the study and again 10 months later. Bullying was assessed by a standardized questionnaire to identify victims, perpetrators, and those who were neither (i.e., neutral). Students were asked to name classmates that fit into one of the three categories. If a student was named on 1 percent of the other students' questionnaires, that student was assigned a score of 1. Students who scored higher than 1 on the scale were then divided into categories based on how they were classified by their classmates. The four categories were perpetrator, victim, victim-perpetrator, or neither. Psychological testing of the students was done by a standardized questionnaire with seven subsets used to identify psychopathologic behaviors.

Results: Fourteen percent of the students were victims of bullying, 17 percent were perpetrators, and 9 percent were victim-perpetrators. Students who were identified as victims at the start of the study were found to have a higher risk of developing social problems. Those students identified as perpetrators were found to be at increased risk of aggressive behavior, and those identified as victim-perpetrators had increased aggression and difficulty externalizing problems compared with students who were identified as neutral. New-onset psychopathologic behaviors at the end of the 10-month study were associated with antecedent bullying experience.

Conclusion: The authors conclude that bullying causes psychopathologic behaviors in the victims and the bully. Because of the impact bullying has on schoolchildren, it is important to develop programs that prevent or decrease bullying among children.